The present invention relates generally to a reflective and transflective liquid crystal display (LCD), and more particularly, to a scattering fringe field optical-compensated (SFFC) reflective and transflective LCD.
Conventional twisted nematic (TN) mode LCD intrinsically has low contrast ratio (CR), narrow viewing angle and large color dispersion. To obtain wider viewing angles for such LCD""s, fringe field is proposed to be applied on the LC molecules thereof, for example, in the LCD with improved viewing angle and transmittance disclosed by U.S. Pat. No. 6,215,542 issued to Lee et al. However, to manufacture the LCD disclosed by Lee et al., a 6-mask process is required, which comprises one more mask process than that for a conventional transmittive TN mode LCD, and the etch process for the indium tin oxide (ITO) electrode thereof is also complicated. On the other hand, a conventional reflective LCD is a TN mode LCD in combination with a reflector, so that the viewing angle thereof is limited by the TN mode under 40 degrees (CR greater than 10:1) and the dichromation thereof is serious (xcex94E(x, y)xe2x89xa70.13). Further, the manufacture process for conventional reflective TN mode LCD is complicated due to the formation of the additional reflector thereof. In addition, a new type of LCD, transflective LCD, gains attention more and more. The above-mentioned problems for the reflective LCD""s are also present for the transflective LCD""s. So far the fringe field technique is not available for the reflective and transflective LCD""s. Another problem introduced by the fringe field scheme is that light leakage results in poor dark state for a normal black mode.
It is therefore desired a reflective and transflective LCD with wide viewing angle, high contrast ratio and low color dispersion.
One object of the present invention is an electrode structure to produce a fringe field in combination with a compensator and a polarizer to improve the viewing angle, contrast ratio and color dispersion for a reflective or transflective LCD.
Another object of the present invention is an electrode structure to produce a fringe field in combination with a compensator and a polarizer to simplify the structure and enhance the brightness of a reflective or transflective LCD.
A scattering fringe field optical-compensated reflective LCD comprises, according to the present invention, a thin film transistor (TFT) plate and a color filter plate spaced apart from each other with a LC layer inserted therebetween. A reflective electrode structure formed on the TFT plate is provided to produce a fringe field applied on the LC layer which has a type of negative dielectric anisotropy and an alignment direction. The reflective electrode structure includes a pixel electrode and a common electrode consisting of a plurality of strips to drive the LC layer for a phase difference by the fringe field, and the retardation thus generated by the LC layer is compensated by a compensator formed on the color filter plate. A polarizer is arranged outside of the pixel cell with its polarization axis at an angle from the extension axis of the compensator. In addition, a scattering film is introduced on the color filter plate side to enhance the brightness.
In a scattering fringe field optical-compensated transflective LCD, according to the present invention, a LC layer of negative dielectric anisotropy is inserted between a TFT plate and a color filter plate. A transflective electrode structure is formed on the TFT plate to produce a fringe field to be applied on the LC layer which has a rubbing direction. The transflective electrode structure includes a pixel electrode and a common electrode consisting of a plurality of strips to drive the LC layer for a phase difference by the fringe field. Two compensators and two polarizers are arranged respectively on the TFT plate and color filter plate. The polarization axis of the polarizer and the extension axis of the compensator are arranged with an angle therebetween. Also, a scattering film is introduced on the color filter plate side to enhance the brightness.